Improper Gaussian signaling schemes for interference-limited communications
Final Report Abstract
This proposal developed novel signaling schemes for interference-limited mobile communication networks. Already today, multiuser interference presents the major limiting factor of the end-to-end performance in wireless communications. In pursuit of efficient interference management schemes, current research focuses on interference coordination by means of a joint precoder design that exploits the channel state information. The vast majority of these works assumes that the transmitted signals are distributed as proper Gaussian random signals, which are known to be optimal when the system is not interference-limited. Recently, alternative signaling schemes that deviate from these standard assumptions have been proposed in the literature. It has been shown that the transmission of improper Gaussian signals, whose real and imaginary parts are correlated and/or have unequal power, outperform proper Gaussian signals in various interference-limited networks. This project studied improper signaling schemes for different interference-limited networks. It achieved the following: We provide insights on when improper signaling enables better performance than its proper counterpart. We designed algorithms that optimize the transmission parameters for general interference channels. An improper signaling scheme contains not only the parameters associated with a proper scheme, but also additional ones that describe the impropriety of the signal, which makes the optimization more challenging. We applied improper signaling to underlay cognitive radio scenarios, which can be regarded as a paradigm for low-cooperative multiuser networks. In these scenarios, the interference is managed by setting interference constraints, so that its effect can be upper-bounded and thereby require less cooperation. We explored new interference constraints taking impropriety into account, as well as the optimization of the transmission parameters subject to these constraints. We considered two main performance metrics, namely achievable rate and energy efficiency, and showed that improper Gaussian signaling can substantially outperform proper Gaussian signaling in terms of both achievable rate and energy efficiency in various interference-limited systems such as the K-user SISO and MIMO Interference Channels (ICs), 2-user SISO IC, SISO Z-IC, underlay cognitive radio, and broadcast channels. We also accounted for imperfect knowledge of the channel state information at the transmitter and imperfections in the hardware.
Publications
- “Information-theoretic analysis of a family of improper discrete constellations,” Entropy, vol. 20,
I. Santamaria, P. M. Crespo, C. Lameiro, and P. J. Schreier
(See online at https://doi.org/10.3390/e20010045) - “Benefits of improper signaling for overlay cognitive radio,” in Proc. IEEE Global Commun. Conf. (GLOBECOM), Waikoloa, HI, Dec. 2019
C. Lameiro, I. Santamaria, and P. J. Schreier
(See online at https://doi.org/10.1109/GLOBECOM38437.2019.9013604) - “Energy-efficient design for underlay cognitive radio using improper signaling,” in Proc. ICASSP, pp. 4769–4773, Brighton, UK, 2019
M. Soleymani, C. Lameiro, P. J. Schreier, and I. Santamaria
(See online at https://doi.org/10.1109/ICASSP.2019.8683029) - “Ergodic rate for fading interference channels with proper and improper Gaussian signaling,” Entropy, vol. 21
M. Soleymani, I. Santamaria, C. Lameiro, and P. J. Schreier
(See online at https://doi.org/10.3390/e21100922) - “Improper Gaussian signaling for multipleaccess channels in underlay cognitive radio,” IEEE Trans. Commun., vol. 67, pp. 1817–1830, Mar. 2019
C. Lameiro, I. Santamaria, and P. J. Schreier
(See online at https://doi.org/10.1109/TCOMM.2018.2880765) - “Improper signaling for SISO two-user interference channels with additive asymmetric hardware distortion,” IEEE Trans. Commun., vol. 67, no. 12, pp. 8624–8638, Dec. 2019
M. Soleymani, C. Lameiro, I. Santamaria, and P. J. Schreier
(See online at https://doi.org/10.1109/TCOMM.2019.2939310) - “Maximally improper signaling in underlay MIMO cognitive radio networks,” IEEE Trans. Signal Process., vol. 67, pp. 6241–6255, 15 Dec. 2019
C. Lameiro, I. Santamaria, P. J. Schreier, and W. Utschick
(See online at https://doi.org/10.1109/TSP.2019.2953665) - “Robust improper signaling for two-user SISO interference channels,” IEEE Trans. Commun., vol. 67, no. 7, pp. 4709–4723, July 2019
M. Soleymani, C. Lameiro, I. Santamaria, and P. J. Schreier
(See online at https://doi.org/10.1109/TCOMM.2019.2910549) - “Improper Gaussian signaling for the K-user MIMO interference channels with hardware impairments,” IEEE Trans. Veh. Technol., vol. 69, no. 10, pp. 11632-11645, Oct. 2020
M. Soleymani, I. Santamaria, and P. J. Schreier
(See online at https://doi.org/10.1109/TVT.2020.3015558)
